Portable wireless communication devices such as pagers and cellular phones are extensively used today. For example, conventional wireless messaging devices give the user full text capability and make return phone calls less necessary by providing access to everything from a quick way to get to information on the meetings for the day to the local movie listings to the latest global news update. The more elaborate, customizable wireless messaging devices combine the benefits and flexibility of two-way messaging, software applications and personal computer connectivity with the wear-ability and convenience of a conventional wireless messaging device.
Electronic computing devices are also extensively used today. The portability of the new electronic organizers combined with their longer battery life, larger memories, and safe storage of information has caused a growth in popularity of these devices over the past few years. Increased efficiency from functions such as the synchronization with a personal information manager has proven a major benefit for users in both their personal and business lives.
Recently, there is a trend towards the integration of wireless communication devices and both portable and fixed types of electronic computing devices. Manufacturers of wireless communication devices, manufacturers of electronic computing devices, and wireless service providers are teaming up to produce these integrated services and products including wireless applications capable of receiving text, numeric, and binary messages from the wireless communication modules. These enterprise and consumer applications give electronic computing users the capability to receive wireless e-mail, up-to-the-minute news and stock reports, remote updates on interest rates and financial information, weather warnings, and many other capabilities whose applications are yet to be imagined. The integration of these two complimentary devices also allows corporations to develop mission-critical solutions that keep their mobile workers updated with vital information such as price lists, competitive news, and calendar updates.
Two problems resulting from the integration of wireless communication modules and electronic computing devices are the limited antenna space for the wireless communication module and the degradation of performance of the wireless communication module due to electromagnetic interference (EMI) from the electronic computing device
EMI can affect an electronic system either by the mechanism of conduction, radiation, or a combination of both. EMI control is a difficult design aspect for wireless communication module integration into the electronic computing device since there are so many combinations of EMI sources and mechanisms in the electronic computing device. Additionally, the very high sensitivity of the wireless communication module's receiver and the close proximity of its antenna to the circuitry of the electronic computing device make it very susceptible to EMI. This high noise environment creates receiver desensitization when the undesired EMI signal occurs at the same frequency as the receive frequency, or at a number of other frequencies sensitive to the receiver circuitry (such as the intermediate frequency). Since the receiver cannot differentiate between the desired and undesired signals, the undesired signal can block out the desired signal to desensitize or lower the sensitivity threshold of the receiver. If the amplitude level of the undesired signal can be lowered enough using EMI control techniques, the receiver's sensitivity threshold is not degraded or degraded an allowable amount.
Typically, EMI control is accomplished by re-designing the electronic computing device with EMI techniques in mind. For example, making the housing of the electronic computing device a shielded box, using a dedicated circuit board layer as the ground-plane, using a ground-plane area underneath the wireless communication module, or modifying the electronic circuit design to reduce the EMI emissions from the electronic computing device. Since the electronic computing device is usually already in existence, and most manufacturers do not want to make changes to their electronic computing device, these type of major design modifications are not desirable.
What is needed is a wireless communication module with reduced susceptibility to the EMI emissions of the electronic computing device which fits within the space limitations of the electronic computing device.